Slurry pump front guard plate and preparation method thereof

Abstract

The invention provides a slurry pump front protective plate and a preparation method thereof, and belongs to the technical field of casting of rock breaking slurry pump front protective plates, and the preparation method comprises the following steps: step 1) preparing a prefabricated body; the prefabricated body is a ceramic prefabricated body, and the flowing speed of molten metal can be increased; (2) the prefabricated body is placed in a slurry pump front protection plate mold, then molten metal is poured into the slurry pump front protection plate mold, the slurry pump front protection plate mold is filled with the molten metal, meanwhile, the prefabricated body is wrapped, the molten metal is infiltrated into a set structure of the prefabricated body, and a front protection plate rough blank is obtained; wherein the molten metal is molten metal of a high-hardness wear-resistant alloy; and (3) carrying out heat treatment and processing on the rough blank of the front guard plate to obtain the front guard plate of the slurry pump. The ceramic preform of the spiral structure is high in hardness and strength, cracks cannot penetrate through the ceramic, meanwhile, metallurgical bonding exists between the high-hardness wear-resistant alloy matrix and the ceramic during pouring, the bonding force is large, crack propagation of high-hardness alloy cracking can be resisted, and the fracture toughness of the front protection plate is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of casting a front guard plate of a rock-breaking slurry pump, and in particular relates to a front guard plate of a slurry pump and a preparation method thereof. Background Art

[0002] As an important mechanical equipment widely used in mining, power plants, dredging, metallurgy, chemical industry, building materials and petroleum industries, the main function of slurry pump is to increase the energy of solid-liquid mixed medium through the rotation of the impeller, so as to realize the medium transportation. In the working process of slurry pump, the front guard plate, as one of the key flow-through components, undertakes the important task of protecting the pump body and preventing solid particles from directly impacting the impeller. Therefore, the quality and performance of the front guard plate are directly related to the overall operating efficiency and service life of the slurry pump.

[0003] Centrifugal casting technology has been widely used in the preparation of slurry pump front guard plates due to its unique advantages. It is a technology and method that injects liquid metal into a high-speed rotating mold, uses centrifugal force to fill the mold with molten metal and form a casting. This technology has the following significant characteristics: centrifugal force helps the molten metal to be evenly distributed in the radial direction, reduces defects such as pores and slag inclusions, and improves the mechanical and physical properties of the casting. Cylindrical inner holes can be produced without a core, which is especially suitable for the production of long tubular castings, reducing the ratio of the wall thickness of the casting to the length or diameter, and simplifying the production process. When forming castings, centrifugal force can improve the metal's filling capacity, making it easier for castings to form thin-walled structures.

[0004] The existing front guard plate is usually made of a single alloy by centrifugal casting. However, when the centrifugal casting speed is high, the carbides of the single alloy will be concentrated on the outside of the front guard plate, and the internal stress will form cracks on the front guard plate, resulting in poor fracture toughness of the front guard plate. When the centrifugal casting speed is low, the carbide content of the outer layer is small, and the hardness and wear resistance of the front guard plate are insufficient. Therefore, the existing slurry pump front guard plate has insufficient mechanical properties. Summary of the invention

[0005] Therefore, the present invention provides a slurry pump front guard plate and a preparation method thereof, the main purpose of which is to improve the mechanical properties of the slurry pump front guard plate.

[0006] In order to solve the above problems, on the one hand, the present invention provides a method for preparing a front guard plate of a slurry pump, comprising the following steps:

[0007] Step 1) preparing a preform; the preform is a ceramic preform and can increase the flow rate of the molten metal;

[0008] Step 2) placing the preform in a slurry pump front guard plate mold, and then pouring molten metal into the slurry pump front guard plate mold, so that the molten metal fills the slurry pump front guard plate mold, wraps the preform, and infiltrates into the set structure of the preform to obtain a front guard plate rough blank; wherein the molten metal is a molten metal of a high-hardness and wear-resistant alloy;

[0009] Step 3) heat treating and processing the rough blank of the front guard plate to obtain the front guard plate of the slurry pump.

[0010] Further, in the step 1), the preform is a spiral structure;

[0011] Preferably, the diameter of the preform is 6 to 8 mm;

[0012] Preferably, the number of spiral layers of the preform is 3 to 5;

[0013] Preferably, the thickness of the preform is 1 / 2 to 3 / 4 of the thickness of the slurry pump front guard plate mold;

[0014] Preferably, the central axis of the spiral structure coincides with the central axis of the front guard plate mold of the slurry pump.

[0015] Furthermore, the steps of preparing the preform include:

[0016] Sintering the ceramic raw material in a mold and obtaining the preform after cooling;

[0017] Preferably, the ceramic raw material is one or more of tungsten carbide, titanium carbide, boron carbide, and titanium nitride;

[0018] Preferably, the mold is a spiral structure ceramic mold;

[0019] Preferably, the sintering temperature is 1800-2300° C. and the sintering time is 20-24 hours.

[0020] Furthermore, in step 1), the diameter of the preform is 6 to 8 mm; and / or

[0021] The number of spiral layers of the preform is 3 to 5.

[0022] Furthermore, in the step 2), the raw material components of the high hardness and wear-resistant alloy are, by mass percentage, C: 3.3-3.7wt%, Si: 5.3-5.7wt%, Al: 0.4-0.8wt%, B: 0.1-0.3wt%, V: 8.5-9.0wt%, Nb: 0.4-0.8wt%, Mo: 2.3-2.7wt%, N: 0.06-0.09wt%, La+Ce: 0.2-0.5wt%, and the balance is Fe.

[0023] Furthermore, in the step 2), the step of preparing the molten metal is also included:

[0024] Primary smelting step: smelting the raw material components except rare earth once, and obtaining a master alloy ingot after casting;

[0025] Casting step: refining the master alloy ingot, melting it and then pouring it to obtain the steel ingot; wherein rare earth is added during the refining process;

[0026] Secondary smelting step: performing secondary smelting on the steel ingot to obtain the molten metal after melting.

[0027] Furthermore, in the first smelting step, a vacuum electric frequency induction furnace is used for the first smelting; preferably, the temperature of the first smelting is 1530-1550° C.; the time of the first smelting is 2-2.5 hours; and / or

[0028] In the casting step, the refining treatment temperature is 1530-1550°C; the refining treatment time is 1.5-2h; and / or

[0029] In the secondary smelting step, a vacuum electric frequency induction furnace is used for secondary smelting; preferably, the temperature of the secondary smelting is 1530-1550° C.; and the time of the secondary smelting is 2-2.5 hours.

[0030] Furthermore, in the step 2), the molten metal is poured into the slurry pump front guard plate mold by centrifugal casting;

[0031] Preferably, the centrifugal casting temperature is 1520-1550°C;

[0032] Preferably, the initial centrifugal speed is 600-800 r / min; when centrifugal casting is performed to 1 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 800-1000 r / min; when centrifugal casting is performed to 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1000-1200 r / min; when centrifugal casting is performed to 3 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1200-1500 r / min.

[0033] Furthermore, in the step 3), heat treating the rough front guard plate includes: performing normalizing treatment and tempering treatment on the rough front guard plate in sequence;

[0034] Preferably, the normalizing treatment comprises: heating the rough front guard plate blank to 750-800°C at 3-5°C / h, keeping the temperature for 1-2h, then heating the rough front guard plate blank to 1050-1100°C at 1-1.5°C / h, keeping the temperature for 2-3h, and cooling to room temperature to obtain the rough front guard plate blank after normalizing treatment;

[0035] Preferably, the tempering treatment comprises: heating the rough front guard plate after normalizing treatment to 200-250° C. at 1-1.5° C. / h, keeping the temperature for 2-3 hours, and cooling to room temperature to obtain the front guard plate of the slurry pump.

[0036] On the other hand, the present invention provides a slurry pump front guard plate, the slurry pump front guard plate preform, the preform is infiltrated and wrapped with a high-hardness wear-resistant alloy matrix; wherein the preform is a ceramic preform with a spiral structure;

[0037] Preferably, the microstructure of the front guard plate of the slurry pump includes martensite, austenite and carbide, and the martensite is in the form of laths; the volume fraction of the carbide gradually increases from the core to the surface of the front guard plate of the slurry pump;

[0038] Preferably, the volume fraction of carbides on the surface of the front guard plate of the slurry pump is 67-70%;

[0039] Preferably, the carbide includes VC, M 7 C 3 and Mo 2 C; the VC is spherical and forms a coherent crystal plane with the austenite; the M 7 C 3 Skeleton-shaped.

[0040] Furthermore, the surface hardness of the front guard plate of the slurry pump is ≥70HRC, and the impact toughness is ≥8J / cm 2 ;

[0041] Preferably, the front guard plate of the slurry pump is obtained by any of the preparation methods of the front guard plate of the slurry pump described above.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] 1. The present invention provides a method for preparing a front guard plate of a slurry pump, which comprises preparing a ceramic preform with a spiral structure, placing the preform in a mold for the front guard plate of a slurry pump, and then pouring a molten metal of a high-hardness and wear-resistant alloy into the mold for the front guard plate of the slurry pump, so that the molten metal of the high-hardness and wear-resistant alloy fills the mold for the front guard plate of the slurry pump to obtain a rough blank of the front guard plate; then heat-treating and processing the rough blank of the front guard plate to obtain the front guard plate of the slurry pump; based on the above method, the present invention adds a ceramic preform inside the front baffle, on the one hand, the ceramic material itself has high hardness and strength, and cracks are difficult to penetrate the ceramic, and at the same time During casting, the high-hardness and wear-resistant alloy matrix and the ceramic are metallurgically bonded with each other, and the bonding force is relatively large, which can resist the crack propagation of the high-hardness alloy cracks, thereby improving the fracture toughness of the front guard plate; on the other hand, the preform is beneficial to increase the flow rate of the molten metal, ensure the density of the high-hardness and wear-resistant alloy matrix, and at the same time increase the fluidity of the alloy, which is beneficial to improve the bonding ability between the alloy and the ceramic, and achieve strong support for the outer layer of high-hardness and wear-resistant alloy, ensuring the high hardness and high wear resistance of the outer layer of high-hardness and wear-resistant alloy, thereby ensuring that the front guard plate of the slurry pump has high fracture toughness, high hardness and high wear resistance.

[0044] 2. Furthermore, the preform adopts a spiral structure. The spiral shape has a good guiding effect on the molten metal fluid and can guide the fluid to flow efficiently along the spiral path; at the same time, the spiral structure can increase the turbulence of the fluid, thereby reducing local friction resistance and improving flow efficiency, which is beneficial to improving the bonding ability between the alloy and the ceramic.

[0045] 3. Furthermore, the present invention adopts a variable speed centrifugal casting process to cast the molten metal of the high hardness and wear-resistant alloy, which is beneficial for the carbides to become smaller under the action of centrifugal force, so that the second phase can further improve the synergistic protection of the matrix structure, that is, the strengthening effect of the second phase is exerted, thereby improving the hardness and wear resistance; at the same time, it is beneficial to remove the gas and slag inclusions in the molten metal of the high hardness and wear-resistant alloy, compensate for the shrinkage of the riser, and make the prepared slurry pump front guard plate have fewer defects; the centrifugal casting process has the effect of increasing the centrifugal force of the molten metal, and has the characteristics of accelerating the flow of the molten metal, which is beneficial for the preform to guide the fluid to flow efficiently and the degree of turbulence along the spiral path, thereby helping to improve the high organizational density, high strength and excellent wear resistance of the front guard plate.

[0046] 4. Furthermore, during the pouring process, carbides (formed in situ between vanadium, niobium, molybdenum and carbon in the molten metal) are offset toward the outer surface of the front guard plate through centrifugal acceleration. When the carbide particles accumulate on the outer surface, their movement stops, thereby forming a relatively uniform carbide-rich layer on the outer surface of the slurry pump front guard plate, thereby improving the wear resistance of the surface of the slurry pump front guard plate.

[0047] 5. On the other hand, the present invention provides a front guard plate of a slurry pump, which is obtained by the above-mentioned preparation method, and the front guard plate of the slurry pump comprises a preform and a high-hardness wear-resistant alloy matrix wrapping the preform; wherein the preform is a ceramic preform with a spiral structure; the microstructure of the front guard plate of the slurry pump comprises martensite, austenite and carbide, and the martensite is in the form of laths; the volume fraction of the carbide gradually increases from the core to the surface of the front guard plate of the slurry pump; the volume fraction of the carbide on the surface of the front guard plate of the slurry pump is 67-70%; the carbide comprises VC, M 7 C 3 and Mo 2 C; the VC is spherical and forms a coherent crystal plane with the austenite; the M 7 C 3 Skeleton-shaped; the surface hardness of the front guard plate of the slurry pump is ≥70HRC, and the impact toughness is ≥8J / cm 2 Among them, the spiral structured ceramic preform has high hardness and strength, and cracks cannot penetrate the ceramic. At the same time, during casting, there is a metallurgical bond between the high-hardness and wear-resistant alloy matrix and the ceramic, and the bonding force is relatively large, which can resist the crack propagation of the high-hardness alloy crack, thereby improving the fracture toughness of the front guard plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0049] Figure 1 is a schematic diagram of a spiral structure ceramic preform in the present invention; wherein, Figure 1 a is the top view of the preform, Figure 1 b is a cross-sectional view of half of the front guard plate of the slurry pump. Figure 1 c is a schematic diagram of the prefabricated body being placed on the front guard plate template of the slurry pump;

[0050] Figure 2 This is a microstructure diagram of a cross section from the core to the surface of the front guard plate of a slurry pump in Example 1 of the present invention;

[0051] Figure 3 is a microhardness variation diagram of the cross section from the core to the surface of the front guard plate of the slurry pump of Example 1 of the present invention;

[0052] Figure 4 is a comparison diagram of the cross-sectional microstructure and precipitated phase size of the front guard plate of the slurry pump in Example 2 of the present invention;

[0053] Figure 5is the grain size and impact toughness of different positions of the front guard plate of the slurry pump of Example 2 of the present invention;

[0054] Figure 6 : is a surface optical microscope comparison diagram of the front guard plate of the slurry pump of Example 1 and Example 3 of the present invention;

[0055] Figure 7 is a comparison diagram of the hardness of different parts of the front guard plate of the slurry pump in Example 1 and Example 3 of the present invention;

[0056] Figure 8 It is a comparison chart of the impact toughness and 100-hour wear loss weight of the front guard plate of the slurry pump of Example 1 of the present invention and Comparative Example 1;

[0057] Fig. 9 The near-surface microstructures of the front guard plates of the slurry pumps of Example 1 and Comparative Example 2 of the present invention;

[0058] Fig.10 It is a comparison of the friction coefficient of the surface layer of the front guard plate of the slurry pump of Example 1 of the present invention and Comparative Example 2;

[0059] Fig.11 The morphology of the wear damage on the front guard plate of the slurry pump in Example 1 of the present invention and Comparative Example 3;

[0060] Fig.12 is a comparison diagram of the impact toughness of different parts of the front guard plate of the slurry pump of Example 1 of the present invention and Comparative Example 4;

[0061] The accompanying drawings are marked as: 1-high hardness and wear-resistant alloy, 2-preform, 3-slurry pump front guard plate mold. DETAILED DESCRIPTION

[0062] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0063] In one aspect, the present invention provides a method for preparing a front guard plate of a slurry pump, comprising the following steps:

[0064] Step 1) sintering the ceramic raw material in a mold, and obtaining a preform after cooling; the preform is a ceramic preform and has a spiral structure (i.e., a set structure);

[0065] Wherein, the spiral structure is a disc-shaped spiral structure (i.e., a spiral structure that spirals around at least one circle on a plane, similar to a mosquito coil-like structure); the diameter of the preform is 6 to 8 mm; the number of spiral layers of the preform is 3 to 5 layers; the thickness of the preform is 1 / 2 to 3 / 4 of the thickness of the slurry pump front guard plate mold; the central axis of the spiral structure coincides with the central axis of the slurry pump front guard plate mold; preferably, the ceramic raw material is one or more of tungsten carbide, titanium carbide, boron carbide, and titanium nitride; preferably, the mold is a spiral structure ceramic mold; preferably, the sintering temperature is 1800 to 2300°C; the sintering time is 20 to 24 hours; wherein, the diameter of the preform refers to the maximum diameter of the cylinder surrounded by the spiral structure; the number of layers of the preform refers to the number of layers of the spiral structure rotating around the central axis (i.e., the number of turns it spirals around on a plane);

[0066] Step 2) placing the preform in a slurry pump front guard plate mold, and then pouring the molten metal of the high-hardness wear-resistant alloy into the slurry pump front guard plate mold by centrifugal casting, so that the molten metal of the high-hardness wear-resistant alloy fills the slurry pump front guard plate mold, wraps the preform, and infiltrates into the spiral structure of the preform to obtain a rough blank of the front guard plate;

[0067] The central axis of the spiral structure coincides with the central axis of the mold of the front guard plate of the slurry pump; the temperature of centrifugal casting is 1520-1550°C; preferably, the initial centrifugal speed is 600-800r / min; when centrifugal casting is performed to 1 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 800-1000r / min; when centrifugal casting is performed to 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1000-1200r / min; when centrifugal casting is performed to 3 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1200-1500r / min;

[0068] The preparation of the molten metal of the high-hardness wear-resistant alloy comprises the following steps:

[0069] The first smelting step is to smelt the raw material components except the rare earth in a vacuum electric frequency induction furnace, and obtain a master alloy ingot after pouring; wherein the first smelting temperature is 1530-1550° C. and the first smelting time is 2-2.5 hours;

[0070] Casting step: refining the master alloy ingot, and then pouring it after melting to obtain a steel ingot; wherein rare earth is added during the refining process; the refining temperature is 1530-1550° C.; the refining time is 1.5-2 hours;

[0071] Secondary smelting step: the steel ingot is subjected to secondary smelting in a vacuum electric frequency induction furnace to obtain a high-hardness wear-resistant alloy molten metal after melting; wherein the secondary smelting temperature is 1530-1550°C; and the secondary smelting time is 2-2.5 hours;

[0072] Wherein, the raw material components of the high hardness wear-resistant alloy are, by mass percentage: C: 3.3-3.7wt%, Si: 5.3-5.7wt%, Al: 0.4-0.8wt%, B: 0.1-0.3wt%, V: 8.5-9.0wt%, Nb: 0.4-0.8wt%, Mo: 2.3-2.7wt%, N: 0.06-0.09wt%, La+Ce: 0.2-0.5wt%, and the balance is Fe;

[0073] Step 3) heat treating and processing the rough blank of the front guard plate to obtain the front guard plate of the slurry pump;

[0074] The heat treatment of the rough blank of the front guard plate includes: performing normalizing treatment and tempering treatment on the rough blank of the front guard plate in sequence;

[0075] Preferably, the normalizing treatment comprises: heating the rough front guard plate blank to 750-800°C at 3-5°C / h, keeping the temperature for 1-2h, then heating the rough front guard plate blank to 1050-1100°C at 1-1.5°C / h, keeping the temperature for 2-3h, and cooling to room temperature to obtain the rough front guard plate blank after normalizing treatment;

[0076] Preferably, the tempering treatment comprises: heating the rough blank of the front guard plate after normalizing treatment to 200-250°C at 1-1.5°C / h, keeping the temperature for 2-3h, and cooling to room temperature to obtain the front guard plate of the slurry pump.

[0077] Based on the above method, the present invention adds a ceramic preform with a spiral structure inside the front baffle. On the one hand, the ceramic material itself has high hardness and strength, and cracks are difficult to penetrate the ceramic. At the same time, during casting, the high-hardness and wear-resistant alloy matrix and the ceramic are metallurgically bonded, and the bonding force is relatively large, which can resist the crack expansion of the high-hardness alloy crack, thereby improving the fracture toughness of the front guard plate; on the other hand, the spiral-structured ceramic is beneficial to increase the flow rate of the molten metal, ensures the density of the high-hardness and wear-resistant alloy matrix, and increases the flow force of the alloy, which is beneficial to improve the bonding ability between the alloy and the ceramic, and realizes strong support for the outer layer of high-hardness and wear-resistant alloy, ensuring the high hardness and high wear resistance of the outer layer of high-hardness and wear-resistant alloy, thereby ensuring that the front guard plate of the slurry pump has high fracture toughness, as well as high hardness and high wear resistance.

[0078] Based on the above components of high-hardness wear-resistant alloy, Al is dissolved in the matrix, which can increase the activity of C in austenite and the martensite transformation temperature. Among them, the increase in C activity is conducive to the in-situ self-generation of multi-scale ceramic particles (i.e. carbides) with other elements, such as VC, Cr 7 C 3 , Fe 7 C 3 and Mo 2C, etc. These carbides are conducive to the realization of second phase strengthening and can also effectively refine the grains, thereby improving the mechanical properties of the slurry pump front guard plate through second phase strengthening and grain refinement strengthening; the increase in martensite transformation temperature can increase the content of lath martensite in the matrix during air cooling, thereby improving the strength and hardness of the matrix; among them, the in-situ self-generation is due to VC, NbC, and Mo 2 The formation Gibbs free energy of C and other carbides is very low, which ensures that the carbides are formed directly during the casting process rather than precipitating from the matrix through solid-state phase transformation.

[0079] For the slurry pump front guard plate of the present application, the alloying degree is relatively high, more alloying elements can form more carbides with C, and the size of the carbides is getting larger and larger, changing from fine spheres to thick rods, resulting in stress concentration and preferential failure, that is, the strength and toughness of the slurry pump front guard plate decreases; the greater the alloying, the larger the solidification temperature range of the alloy and the greater the viscosity. Therefore, rare earth elements La and Ce are added to the components, and grain refinement is achieved through the synergistic effect of Al element and rare earth. This is because the atomic radius of rare earth is larger than that of aluminum, and its properties are relatively active. It is very easy to fill the surface defects of the alloy phase when melted in the aluminum molten pool, so that the surface tension at the interface between the new and old phases is reduced, and the growth rate of the crystal nucleus is increased; at the same time, a surface active film can be formed between the grains and the molten liquid to prevent the generated grains from growing, that is, under the synergistic effect of Al element and rare earth, the grain size of the carbide is smaller (for example, VC, Cr 7 C 3 、Mo 2 C is micrometer scale, Cr 23 C 6 is nanoscale), thereby improving the toughness of the front guard plate of the slurry pump.

[0080] On the other hand, the present invention provides a front guard plate of a slurry pump, the front guard plate of the slurry pump comprises a preform, the preform is infiltrated and wrapped with a high-hardness wear-resistant alloy matrix; wherein the preform is a ceramic preform with a spiral structure;

[0081] Preferably, the microstructure of the front guard plate of the slurry pump includes martensite, austenite and carbide, and the martensite is in the form of laths; the volume fraction of carbides gradually increases from the core to the surface of the front guard plate of the slurry pump; the volume fraction of carbides on the surface of the front guard plate of the slurry pump is 67-70%; the carbides include VC, M 7 C 3 and Mo 2 C; VC is spherical and forms a coherent crystal plane with austenite; M 7 C 3 Skeleton-shaped.

[0082] Furthermore, the surface hardness of the front guard plate of the slurry pump is ≥70HRC and the impact toughness is ≥8J / cm 2 ;

[0083] Preferably, the front guard plate of the slurry pump is obtained by any of the above-mentioned methods for preparing the front guard plate of the slurry pump.

[0084] The volume fraction of carbides on the surface of the front guard plate of the slurry pump is high, which can improve the wear resistance of the surface of the front guard plate of the slurry pump; VC can improve the strength and hardness of the front guard plate of the slurry pump, and it forms a coherent interface with the surrounding matrix in a spherical shape, and Cr 7 C 3 , Fe 7 C 3 The skeleton shape is beneficial to the coordinated deformation during the wear process, thereby inhibiting the spalling of the material matrix during the wear process; the high degree of alloying is beneficial to increasing the martensite transformation temperature, thereby increasing the content of plate martensite during air cooling and refining the martensite size, thereby improving the strength and toughness of the slurry pump front guard plate.

[0085] The present invention is further described below in conjunction with specific embodiments.

[0086] The raw material components of the high hardness and wear-resistant alloys of the embodiments and comparative examples are shown in Table 1.

[0087] Table 1 shows the raw material components (wt%) of the high hardness and wear resistant alloys of the embodiments of the present invention and the comparative examples.

[0088] C Si Al B V Nb Mo N Rare Earth Fe Example 1 3.5 5.5 0.6 0.2 8.7 0.6 2.5 0.08 0.3 Remain Example 2 3.3 5.3 0.5 0.1 8.6 0.3 2.3 0.06 0.2 Remain Example 3 3.5 5.5 0.6 0.2 8.7 0.6 2.5 0.08 0 Remain Comparative Example 3 2 5.5 0.6 0.2 6.5 0.6 2.5 0.08 0.3 Remain

[0089] Example 1

[0090] This embodiment provides a method for preparing a front guard plate of a slurry pump, which specifically includes the following steps:

[0091] Step 1) sintering the ceramic raw material in a mold, and obtaining a preform after cooling; the preform is a ceramic preform with a spiral structure;

[0092] The diameter of the preform is 8 mm; the number of spiral layers of the preform is 4; the thickness of the preform is 1 / 2 of the thickness of the front guard plate mold of the slurry pump; the ceramic raw material is tungsten carbide; the mold is a spiral structure ceramic mold; preferably, the sintering temperature is 1950°C; the sintering time is 22 hours;

[0093] Step 2) placing the preform in a slurry pump front guard plate mold, with the central axis of the spiral structure coinciding with the central axis of the slurry pump front guard plate mold; then pouring the molten metal of the high-hardness wear-resistant alloy into the slurry pump front guard plate mold by centrifugal casting, so that the molten metal of the high-hardness wear-resistant alloy fills the slurry pump front guard plate mold and wraps the preform at the same time, and infiltrates into the spiral structure of the preform, to obtain a rough blank of the front guard plate;

[0094] The temperature of centrifugal casting is 1540℃; the initial centrifugal speed is 650r / min; when the centrifugal casting reaches 1 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 850r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1100r / min; when the centrifugal casting reaches 3 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1250r / min; the centrifugal casting time is 22min;

[0095] The preparation of the molten metal of the high-hardness wear-resistant alloy comprises the following steps:

[0096] The first smelting step: according to the raw material components of Example 1 in Table 1, the raw material components other than rare earth are first smelted in a vacuum electric frequency induction furnace, and a master alloy ingot is obtained after casting; wherein the first smelting temperature is 1540° C.; and the first smelting time is 2 hours;

[0097] Casting steps: refining the master alloy ingot, and then pouring it after melting to obtain a steel ingot; wherein rare earth is added during the refining process; the refining temperature is 1540° C.; and the refining time is 1.6 hours;

[0098] Secondary smelting step: the steel ingot is subjected to secondary smelting in a vacuum electric frequency induction furnace to obtain a high-hardness wear-resistant alloy molten metal after melting; wherein the secondary smelting temperature is 1540°C; and the secondary smelting time is 2 hours;

[0099] Step 3) The rough blank of the front guard plate is loaded into the furnace at room temperature, and then heated to 770°C at 4°C / h, kept warm for 1.5h, and then heated to 1080°C at 1.3°C / h, kept warm for 2.5h, and then cooled to room temperature to obtain the rough blank of the front guard plate after normalizing treatment; the rough blank of the front guard plate after normalizing treatment is tempered, the tempering treatment is carried out by heating to 230°C at 1°C / h, keeping warm for 2.5h, directly air cooling to room temperature, and then machining to obtain the front guard plate of the slurry pump.

[0100] The top view of the preform prepared in this embodiment and the cross-sectional view of the front guard plate of the slurry pump are shown in FIG. Figure 1 As shown in FIG. 1 , it can be seen that the spiral structure preform 1 is infiltrated and wrapped with a high-hardness wear-resistant alloy (matrix) 2, and the central axis of the preform 1 coincides with the central axis of the slurry pump front guard plate mold 3; the microstructure morphology and microhardness changes of the slurry pump front guard plate from the core to the surface are shown in FIG. Figure 2 and Figure 3As shown, it can be found that the carbide content increases from the core to the surface and the distribution becomes finer and more dispersed, and the hardness becomes higher and higher. This is because the centrifugal casting method allows the carbides to migrate to the surface of the front guard plate of the slurry pump, and the centrifugal force also makes the size of the carbides smaller. The fine carbides play a role of second phase strengthening, which is beneficial to improving the hardness of the surface of the front guard plate; at the same time, the ceramic preform with a spiral structure is beneficial to increasing the flow rate of the molten metal, ensuring the density of the high-hardness and wear-resistant alloy matrix, and increasing the flow force of the alloy, which is beneficial to improving the bonding ability between the alloy and the ceramic, achieving strong support for the outer layer of high-hardness and wear-resistant alloy, and further improving the surface hardness.

[0101] Example 2

[0102] This embodiment provides a method for preparing a front guard plate of a slurry pump, which specifically includes the following steps:

[0103] Step 1) sintering the ceramic raw material in a mold, and obtaining a preform after cooling; the preform is a ceramic preform with a spiral structure;

[0104] The diameter of the preform is 6 mm; the number of spiral layers of the preform is 4; the thickness of the preform is 3 / 4 of the thickness of the slurry pump front guard plate mold; the ceramic raw material is tungsten carbide; the mold is a spiral structure ceramic mold; preferably, the sintering temperature is 2200°C; the sintering time is 24 hours;

[0105] Step 2) placing the preform in a slurry pump front guard plate mold, with the central axis of the spiral structure coinciding with the central axis of the slurry pump front guard plate mold; then pouring the molten metal of the high-hardness wear-resistant alloy into the slurry pump front guard plate mold by centrifugal casting, so that the molten metal of the high-hardness wear-resistant alloy fills the slurry pump front guard plate mold and wraps the preform at the same time, and infiltrates into the spiral structure of the preform, to obtain a rough blank of the front guard plate;

[0106] The temperature of centrifugal casting is 1550℃; the initial centrifugal speed is 650r / min; when the centrifugal casting reaches 1 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 850r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1100r / min; when the centrifugal casting reaches 3 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1250r / min; the centrifugal casting time is 23min;

[0107] The preparation of the molten metal of the high-hardness wear-resistant alloy comprises the following steps:

[0108] The first smelting step: according to the raw material components of Example 2 in Table 1, the raw material components other than rare earth are first smelted in a vacuum electric frequency induction furnace, and a master alloy ingot is obtained after casting; wherein the first smelting temperature is 1550° C.; and the first smelting time is 2.5 h;

[0109] Casting steps: refining the master alloy ingot, and then pouring it after melting to obtain a steel ingot; wherein rare earth is added during the refining process; the refining temperature is 1550° C.; and the refining time is 1.8 hours;

[0110] Secondary smelting step: the steel ingot is subjected to secondary smelting in a vacuum electric frequency induction furnace to obtain a high-hardness wear-resistant alloy molten metal after melting; wherein the secondary smelting temperature is 1550°C; and the secondary smelting time is 2.5 hours;

[0111] Step 3) The rough blank of the front guard plate is loaded into the furnace at room temperature, and then heated to 780°C at 4.5°C / h, kept warm for 1.3h, and then heated to 1070°C at 1.5°C / h, kept warm for 2.2h, and then cooled to room temperature to obtain the rough blank of the front guard plate after normalizing treatment; the rough blank of the front guard plate after normalizing treatment is tempered, the tempering treatment is carried out by heating to 220°C at 1.5°C / h, keeping warm for 2.4h, directly air cooling to room temperature, and then machining to obtain the front guard plate of the slurry pump.

[0112] The microstructure and size comparison of the precipitated phase (carbide) from the core to the surface of the slurry pump front guard plate prepared in this embodiment are as follows: Figure 4 As shown, the grain size and impact toughness at different locations are Figure 5 As shown, it can be found that the size of carbides from the core to the surface becomes smaller and smaller, and the impact toughness becomes higher and higher. This is because fine carbides can significantly refine the grains and disperse the impact stress concentration effect, thereby improving its comprehensive mechanical properties; at the same time, due to the high hardness and strength of the ceramic material itself, cracks are difficult to penetrate the ceramic. During casting, the metallurgical bonding between the high-hardness and wear-resistant alloy matrix and the ceramic has a large bonding force, which can resist the crack expansion of the high-hardness alloy cracking, thereby improving the impact toughness of the front guard plate.

[0113] The above two embodiments are preferred embodiments that adopt the essential features and preferred technical features of the present invention, and the following embodiments are embodiments that adopt the essential features and non-preferred technical features.

[0114] Example 3

[0115] This embodiment provides a method for preparing a front guard plate of a slurry pump, which specifically includes the following steps:

[0116] Step 1) sintering the ceramic raw material in a mold, and obtaining a preform after cooling; the preform is a ceramic preform with a spiral structure;

[0117] The diameter of the preform is 8 mm; the number of spiral layers of the preform is 4; the thickness of the preform is 1 / 2 of the thickness of the front guard plate mold of the slurry pump; the ceramic raw material is titanium carbide; the mold is a spiral structure ceramic mold; preferably, the sintering temperature is 1850°C; and the sintering time is 20 hours;

[0118] Step 2) placing the preform in a slurry pump front guard plate mold, with the central axis of the spiral structure coinciding with the central axis of the slurry pump front guard plate mold; then pouring the molten metal of the high-hardness wear-resistant alloy into the slurry pump front guard plate mold by centrifugal casting, so that the molten metal of the high-hardness wear-resistant alloy fills the slurry pump front guard plate mold and wraps the preform at the same time, and infiltrates into the spiral structure of the preform, to obtain a rough blank of the front guard plate;

[0119] The temperature of centrifugal casting is 1540℃; the initial centrifugal speed is 650r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1000r / min; the centrifugal casting time is 23min;

[0120] The preparation of the molten metal of the high-hardness wear-resistant alloy comprises the following steps:

[0121] The first smelting step: according to the raw material components of Example 3 in Table 1, the raw material components other than rare earth are first smelted in a vacuum electric frequency induction furnace, and a master alloy ingot is obtained after casting; wherein the first smelting temperature is 1540° C. and the first smelting time is 2 hours;

[0122] Casting steps: refining the master alloy ingot, and then pouring it after melting to obtain a steel ingot; wherein rare earth is added during the refining process; the refining temperature is 1540° C.; and the refining time is 1.6 hours;

[0123] Secondary smelting step: the steel ingot is subjected to secondary smelting in a vacuum electric frequency induction furnace to obtain a high-hardness wear-resistant alloy molten metal after melting; wherein the secondary smelting temperature is 1540°C; and the secondary smelting time is 2 hours;

[0124] Step 3) The rough blank of the front guard plate is loaded into the furnace at room temperature, and then heated to 770°C at 4°C / h, kept warm for 1.5h, and then heated to 1080°C at 1.3°C / h, kept warm for 2.5h, and then cooled to room temperature to obtain the rough blank of the front guard plate after normalizing treatment; the rough blank of the front guard plate after normalizing treatment is tempered, the tempering treatment is carried out by heating to 230°C at 1°C / h, keeping warm for 2.5h, directly air cooling to room temperature, and then machining to obtain the front guard plate of the slurry pump.

[0125] The surface defect comparison and the hardness comparison from the core to the surface of the slurry pump front guard plate prepared in this embodiment and in Example 1 are as follows: Figure 6 and Figure 7 As shown, it can be found that the surface composition of the front guard plate of the slurry pump in this embodiment is segregated, and the hardness is greatly reduced. This is because the rotation speed is increased rapidly during centrifugal casting in this embodiment, which can easily cause composition segregation near the surface, resulting in a large change in the hardness of the prepared front guard plate of the slurry pump from the core to the surface, which will cause stress concentration and accelerate its fracture.

[0126] Comparative Example 1

[0127] This comparative example provides a method for preparing a front guard plate of a slurry pump, which specifically comprises the following steps:

[0128] Step 1) pouring the molten metal of the high-hardness wear-resistant alloy into the front guard plate mold of the slurry pump by centrifugal casting, so that the molten metal of the high-hardness wear-resistant alloy fills the front guard plate mold of the slurry pump to obtain a rough blank of the front guard plate;

[0129] The temperature of centrifugal casting is 1540℃; the initial centrifugal speed is 650 / min; when the centrifugal casting reaches 1 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 850r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1100r / min; when the centrifugal casting reaches 3 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1250r / min; the centrifugal casting time is 22min;

[0130] The preparation of the molten metal of the high-hardness wear-resistant alloy comprises the following steps:

[0131] The first smelting step: according to the raw material components of Example 1 in Table 1, the raw material components other than rare earth are first smelted in a vacuum electric frequency induction furnace, and a master alloy ingot is obtained after casting; wherein the first smelting temperature is 1540° C.; and the first smelting time is 2 hours;

[0132] Casting steps: refining the master alloy ingot, and then pouring it after melting to obtain a steel ingot; wherein rare earth is added during the refining process; the refining temperature is 1540° C.; and the refining time is 1.6 hours;

[0133] Secondary smelting step: the steel ingot is subjected to secondary smelting in a vacuum electric frequency induction furnace to obtain a high-hardness wear-resistant alloy molten metal after melting; wherein the secondary smelting temperature is 1540°C; and the secondary smelting time is 2 hours;

[0134] Step 3) The rough blank of the front guard plate is loaded into the furnace at room temperature, and then heated to 770°C at 4°C / h, kept warm for 1.5h, and then heated to 1080°C at 1.3°C / h, kept warm for 2.5h, and then cooled to room temperature to obtain the rough blank of the front guard plate after normalizing treatment; the rough blank of the front guard plate after normalizing treatment is tempered, the tempering treatment is carried out by heating to 230°C at 1°C / h, keeping warm for 2.5h, directly air cooling to room temperature, and then machining to obtain the front guard plate of the slurry pump.

[0135] The impact toughness of the slurry pump front guard plate prepared in this comparative example is compared with that prepared in Example 1. Figure 8 As shown, it can be found that due to the lack of ceramic preform, the high-hardness wear-resistant alloy has insufficient resistance to crack propagation, and the internal cracks of the high-hardness wear-resistant alloy will quickly become unstable and expand, which will lead to its poor impact toughness. The lack of ceramic preform will also reduce its supporting effect on the high-hardness wear-resistant alloy. Therefore, the wear loss weight of this comparative example is relatively large, resulting in a decrease in its wear performance.

[0136] Comparative Example 2

[0137] This comparative example provides a method for preparing a front guard plate of a slurry pump, which specifically comprises the following steps:

[0138] Step 1) sintering the ceramic raw material in a mold, and obtaining a preform after cooling; the preform is a cylindrical ceramic preform;

[0139] The diameter of the preform is 8 mm; the thickness of the preform is 1 / 2 of the thickness of the front guard plate mold of the slurry pump; the ceramic raw material is tungsten carbide; the mold is a spiral structure ceramic mold; preferably, the sintering temperature is 1950° C.; the sintering time is 22 hours;

[0140] Step 2) placing the preform in a slurry pump front guard plate mold, with the central axis of the preform coinciding with the central axis of the slurry pump front guard plate mold; then pouring the molten metal of the high-hardness wear-resistant alloy into the slurry pump front guard plate mold by centrifugal casting, so that the molten metal of the high-hardness wear-resistant alloy fills the slurry pump front guard plate mold, wraps the preform, and infiltrates into the spiral structure of the preform, to obtain a rough blank of the front guard plate;

[0141] The temperature of centrifugal casting is 1540℃; the initial centrifugal speed is 650r / min; when the centrifugal casting reaches 1 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 850r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1100r / min; when the centrifugal casting reaches 3 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1250r / min; the centrifugal casting time is 22min;

[0142] The preparation of the molten metal of the high-hardness wear-resistant alloy comprises the following steps:

[0143] The first smelting step: according to the raw material components of Example 1 in Table 1, the raw material components other than rare earth are first smelted in a vacuum electric frequency induction furnace, and a master alloy ingot is obtained after casting; wherein the first smelting temperature is 1540° C.; and the first smelting time is 2 hours;

[0144] Casting steps: refining the master alloy ingot, and then pouring it after melting to obtain a steel ingot; wherein rare earth is added during the refining process; the refining temperature is 1540° C.; and the refining time is 1.6 hours;

[0145] Secondary smelting step: the steel ingot is subjected to secondary smelting in a vacuum electric frequency induction furnace to obtain a high-hardness wear-resistant alloy molten metal after melting; wherein the secondary smelting temperature is 1540°C; and the secondary smelting time is 2 hours;

[0146] Step 3) The rough blank of the front guard plate is loaded into the furnace at room temperature, and then heated to 770°C at 4°C / h, kept warm for 1.5h, and then heated to 1080°C at 1.3°C / h, kept warm for 2.5h, and then cooled to room temperature to obtain the rough blank of the front guard plate after normalizing treatment; the rough blank of the front guard plate after normalizing treatment is tempered, the tempering treatment is carried out by heating to 230°C at 1°C / h, keeping warm for 2.5h, directly air cooling to room temperature, and then machining to obtain the front guard plate of the slurry pump.

[0147] The microstructure morphology of the near outer surface of this comparative example and Example 1 is as follows Fig. 9 It can be found that the ceramic preform of this comparative example is changed from a spiral preform to a cylindrical preform, which has a smaller driving force for the solidification of the molten metal, so the size of the outer carbide is larger than that of the present invention example, and the average friction coefficient is lower than that of Example 1. The test results are shown in Fig.10 .

[0148] Comparative Example 3

[0149] This comparative example provides a method for preparing a front guard plate of a slurry pump, which specifically comprises the following steps:

[0150] Step 1) sintering the ceramic raw material in a mold, and obtaining a preform after cooling; the preform is a ceramic preform with a spiral structure;

[0151] The diameter of the preform is 8 mm; the number of spiral layers of the preform is 4; the thickness of the preform is 1 / 2 of the thickness of the front guard plate mold of the slurry pump; the ceramic raw material is tungsten carbide; the mold is a spiral structure ceramic mold; preferably, the sintering temperature is 1950°C; the sintering time is 22 hours;

[0152] Step 2) placing the preform in a slurry pump front guard plate mold, with the central axis of the spiral structure coinciding with the central axis of the slurry pump front guard plate mold; then pouring the molten metal of the high-hardness wear-resistant alloy into the slurry pump front guard plate mold by centrifugal casting, so that the molten metal of the high-hardness wear-resistant alloy fills the slurry pump front guard plate mold and wraps the preform at the same time, and infiltrates into the spiral structure of the preform, to obtain a rough blank of the front guard plate;

[0153] The temperature of centrifugal casting is 1540℃; the initial centrifugal speed is 650r / min; when the centrifugal casting reaches 1 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 850r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1100r / min; when the centrifugal casting reaches 3 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1250r / min; the centrifugal casting time is 22min;

[0154] The preparation of the molten metal of the high-hardness wear-resistant alloy comprises the following steps:

[0155] The first smelting step: according to the raw material components of comparative example 3 in Table 1, the raw material components other than rare earth are smelted in a vacuum electric frequency induction furnace, and a master alloy ingot is obtained after casting; wherein the first smelting temperature is 1540° C.; and the first smelting time is 2 hours;

[0156] Casting steps: refining the master alloy ingot, and then pouring it after melting to obtain a steel ingot; wherein rare earth is added during the refining process; the refining temperature is 1540° C.; and the refining time is 1.6 hours;

[0157] Secondary smelting step: the steel ingot is subjected to secondary smelting in a vacuum electric frequency induction furnace to obtain a high-hardness wear-resistant alloy molten metal after melting; wherein the secondary smelting temperature is 1540°C; and the secondary smelting time is 2 hours;

[0158] Step 3) The rough blank of the front guard plate is loaded into the furnace at room temperature, and then heated to 770°C at 4°C / h, kept warm for 1.5h, and then heated to 1080°C at 1.3°C / h, kept warm for 2.5h, and then cooled to room temperature to obtain the rough blank of the front guard plate after normalizing treatment; the rough blank of the front guard plate after normalizing treatment is tempered, the tempering treatment is carried out by heating to 230°C at 1°C / h, keeping warm for 2.5h, directly air cooling to room temperature, and then machining to obtain the front guard plate of the slurry pump.

[0159] The comparison of the wear microstructure of the front baffle prepared in this comparative example and the embodiment is as follows: Fig.11As shown, it can be found that the base alloy composition range of this comparative example is not without the high hardness wear-resistant alloy of the present invention. The V and Cr content in the alloy is low, resulting in low carbide content and insufficient surface hardness, resulting in poor wear resistance of the front baffle surface.

[0160] Comparative Example 4

[0161] This comparative example provides a method for preparing a front guard plate of a slurry pump, which specifically comprises the following steps:

[0162] Step 1) sintering the ceramic raw material in a mold, and obtaining a preform after cooling; the preform is a ceramic preform with a spiral structure;

[0163] The diameter of the preform is 8 mm; the number of spiral layers of the preform is 4; the thickness of the preform is 1 / 2 of the thickness of the front guard plate mold of the slurry pump; the ceramic raw material is tungsten carbide; the mold is a spiral structure ceramic mold; preferably, the sintering temperature is 1950°C; the sintering time is 22 hours;

[0164] Step 2) placing the preform in a slurry pump front guard plate mold, with the central axis of the spiral structure coinciding with the central axis of the slurry pump front guard plate mold; then pouring the molten metal of the high-hardness wear-resistant alloy into the slurry pump front guard plate mold by centrifugal casting, so that the molten metal of the high-hardness wear-resistant alloy fills the slurry pump front guard plate mold and wraps the preform at the same time, and infiltrates into the spiral structure of the preform, to obtain a rough blank of the front guard plate;

[0165] The temperature of centrifugal casting is 1540℃; the initial centrifugal speed is 650r / min; when the centrifugal casting reaches 1 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 850r / min; when the centrifugal casting reaches 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1100r / min; when the centrifugal casting reaches 3 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1250r / min; the centrifugal casting time is 22min;

[0166] The preparation of the molten metal of the high-hardness wear-resistant alloy comprises the following steps:

[0167] The first smelting step: according to the raw material components of Example 1 in Table 1, the raw material components other than rare earth are first smelted in a vacuum electric frequency induction furnace, and a master alloy ingot is obtained after casting; wherein the first smelting temperature is 1540° C.; and the first smelting time is 2 hours;

[0168] Casting steps: refining the master alloy ingot, and then pouring it after melting to obtain a steel ingot; wherein rare earth is added during the refining process; the refining temperature is 1540° C.; and the refining time is 1.6 hours;

[0169] Secondary smelting step: the steel ingot is subjected to secondary smelting in a vacuum electric frequency induction furnace to obtain a high-hardness wear-resistant alloy molten metal after melting; wherein the secondary smelting temperature is 1540°C; and the secondary smelting time is 2 hours;

[0170] Step 3) The rough blank of the front guard plate is loaded into the furnace at room temperature, and then heated to 770°C at 4°C / h, kept warm for 1.5h, and then heated to 1200°C at 1.3°C / h, kept warm for 2.5h, and then cooled to room temperature to obtain the rough blank of the front guard plate after normalizing treatment; the rough blank of the front guard plate after normalizing treatment is tempered, the tempering treatment is carried out by heating to 300°C at 1°C / h, keeping warm for 2.5h, directly air cooling to room temperature, and then machining to obtain the front guard plate of the slurry pump.

[0171] The impact toughness of the front baffle prepared in this comparative example and in Example 1 is compared. Fig.12 As shown, the normalizing temperature and tempering temperature of this comparative example are both higher than the temperature range described in the present invention, so the carbide growth will be aggravated during the heat treatment process, which is not conducive to its strength and toughness.

[0172] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0173] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. These improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a front guard plate of a slurry pump, characterized in that: The following steps are involved: Step 1) preparing a preform; the preform is a ceramic preform that can increase the flow rate of the molten metal; Step 2) placing the preform in a slurry pump front guard plate mold, and then pouring molten metal into the slurry pump front guard plate mold, so that the molten metal fills the slurry pump front guard plate mold, wraps the preform, and infiltrates into the set structure of the preform to obtain a front guard plate rough blank; wherein the molten metal is a molten metal of a high-hardness and wear-resistant alloy; Step 3) heat treating and processing the rough blank of the front guard plate to obtain the front guard plate of the slurry pump.

2. The method for preparing a front guard plate of a slurry pump according to claim 1, characterized in that: In the step 1), the preform is a spiral structure; Preferably, the diameter of the preform is 6 to 8 mm; Preferably, the number of spiral layers of the preform is 3 to 5; Preferably, the thickness of the preform is 1 / 2 to 3 / 4 of the thickness of the slurry pump front guard plate mold; Preferably, the central axis of the spiral structure coincides with the central axis of the front guard plate mold of the slurry pump.

3. The method for preparing a front guard plate of a slurry pump according to claim 2, characterized in that: The steps of preparing the preform include: Sintering the ceramic raw material in a mold and obtaining the preform after cooling; Preferably, the ceramic raw material is one or more of tungsten carbide, titanium carbide, boron carbide, and titanium nitride; Preferably, the mold is a ceramic mold with a spiral structure; Preferably, the sintering temperature is 1800-2300° C. and the sintering time is 20-24 hours.

4. The method for preparing a front guard plate of a slurry pump according to claim 1, characterized in that: In the step 2), the raw material components of the high hardness and wear-resistant alloy are, by mass percentage, C: 3.3-3.7wt%, Si: 5.3-5.7wt%, Al: 0.4-0.8wt%, B: 0.1-0.3wt%, V: 8.5-9.0wt%, Nb: 0.4-0.8wt%, Mo: 2.3-2.7wt%, N: 0.06-0.09wt%, La+Ce: 0.2-0.5wt%, and the balance is Fe.

5. The method for preparing a front guard plate of a slurry pump according to claim 1 or 4, characterized in that: In the step 2), the step of preparing the molten metal is also included: Primary smelting step: smelting the raw material components except rare earth once, and obtaining a master alloy ingot after casting; Casting step: refining the master alloy ingot, melting it and then pouring it to obtain the steel ingot; wherein rare earth is added during the refining process; Secondary smelting step: performing secondary smelting on the steel ingot to obtain the molten metal after melting.

6. The method for preparing a front guard plate of a slurry pump according to claim 5, characterized in that: In the primary smelting step, a vacuum electric frequency induction furnace is used for primary smelting; preferably, the primary smelting temperature is 1530-1550° C.; the primary smelting time is 2-2.5 hours; and / or In the casting step, the refining treatment temperature is 1530-1550°C; the refining treatment time is 1.5-2h; and / or In the secondary smelting step, a vacuum electric frequency induction furnace is used for secondary smelting; preferably, the temperature of the secondary smelting is 1530-1550° C.; and the time of the secondary smelting is 2-2.5 hours.

7. The method for preparing a front guard plate of a slurry pump according to claim 1, characterized in that: In the step 2), the molten metal is poured into the slurry pump front guard plate mold by centrifugal casting; Preferably, the centrifugal casting temperature is 1520-1550°C; Preferably, the initial centrifugal speed is 600-800 r / min; when centrifugal casting is performed to 1 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 800-1000 r / min; when centrifugal casting is performed to 1 / 2 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1000-1200 r / min; when centrifugal casting is performed to 3 / 4 of the thickness of the front baffle of the slurry pump, the centrifugal speed is increased to 1200-1500 r / min.

8. The method for preparing a front guard plate of a slurry pump according to claim 1, characterized in that: In the step 3), heat treating the rough front guard plate includes: performing normalizing treatment and tempering treatment on the rough front guard plate in sequence; Preferably, the normalizing treatment comprises: heating the rough front guard plate blank to 750-800°C at 3-5°C / h, keeping the temperature for 1-2h, then heating the rough front guard plate blank to 1050-1100°C at 1-1.5°C / h, keeping the temperature for 2-3h, and cooling to room temperature to obtain the rough front guard plate blank after normalizing treatment; Preferably, the tempering treatment comprises: heating the rough front guard plate after normalizing treatment to 200-250° C. at 1-1.5° C. / h, keeping the temperature for 2-3 hours, and cooling to room temperature to obtain the front guard plate of the slurry pump.

9. A front guard plate of a slurry pump, characterized in that: The slurry pump front guard plate comprises a preform, which is infiltrated and wrapped with a high-hardness wear-resistant alloy matrix; wherein the preform is a ceramic preform with a spiral structure; Preferably, the microstructure of the front guard plate of the slurry pump includes martensite, austenite and carbide, and the martensite is in the form of laths; the volume fraction of the carbide gradually increases from the core to the surface of the front guard plate of the slurry pump; Preferably, the volume fraction of carbides on the surface of the front guard plate of the slurry pump is 67-70%; Preferably, the carbides include VC, M7C3 and Mo2C; the VC is spherical and forms a coherent crystal plane with the austenite; and the M7C3 is skeletal.

10. The front guard plate of the slurry pump according to claim 9, characterized in that: The surface hardness of the front guard plate of the slurry pump is ≥70HRC, and the impact toughness is ≥8J / cm 2 ; Preferably, the front guard plate of the slurry pump is obtained by the preparation method of the front guard plate of the slurry pump according to any one of claims 1 to 8.

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